NL2026594B1 - Polymer composite comprising spent grains - Google Patents

Abstract

The invention concerns a polymer composite comprising: a. polymer in an amount of 5-94.5% by weight of the overall weight; b. milled spent grains in an amount of at least 5% by weight of the overall weight; c. plasticizer in an amount from 5 — 50% w/w of component b); d. optional filler, and e. optional additive, wherein c) is a solid plasticizer with a melting temperature in the range of 55 to 210°. The invention also concerns a process for its preparation, an intermediate, and a solid article comprising the polymer composite.

Description

Title: Polymer composite comprising spent grains Technical Field This invention concerns a polymer composite comprising milled spent grains that are a by- product of the brewing or distilling industry. More in particular, this invention concerns a polymer composite comprising an increased amount of milled spent grains. Background Art Distillers’ grains are the cereal by-product of a fermentation or distillation process, whereas brewers’ grain, or brewer's spent grain (BSG), usually specifically refers to the residual barley (or in a mixture with other cereal grains or grain products) produced as a by-product of beer brewing, collected before fermentation of the wort. The majority of brewers’ grain comprises barley malt grain husks in combination with parts of the pericarp and seed coat layers of the barley. Distillers’ grains are normally a mix of corn, rice and other grains that have come from either brewing or the production of ethanol biofuels. For the purposes of this patent, the use of the term spent grains will encompass distillers’ grains and brewers’ grains. Distillers’ grains are available as wet distillers grains (WDG), containing primarily unfermented grain residues (protein, fibre, fat and up to 70% moisture), and as dried distillers grains with solubles (DDGS), which is WDG that has been dried with the concentrated thin stillage to 10-12% moisture or less. DDGS is a complex composition of protein (26.8-33.7% dry weight basis) carbohydrates (39.2-61.9%), oils (3.5-12.8%), and ash (2.0-9.8%). The definition of spent grains refers to dried distillers’ grains and/or dried brewers’ spent grain that have optionally been further solvent treated to remove solubles and/or oils. It is known that DDGS has been compounded into polypropylene, polyethylene, acrylonitrile butadiene styrene, phenolic resins, polyurethane and polyamide up to 30% w/w loading levels, with and without the aid of compatibilizers.

It is similarly known that DDGS has been compounded into polylactic acid, polyhydroxyalkanoate, poly(butylene succinate}, poly(butylene adipate-co-terephthalate), and blends thereof, up to 30% w/w loading levels, with and without the aid of compatibilizers and lubricants.

22. The use of DDGS, plasticized with either water or an aqueous solution of urea, is further covered in US patent 10,513,063 as a biomaterial for the preparation of injection moulded articles. lt is also known that DDGS is a feed source in the microbial production of D-lactic acid, which in turn is the precursor in the production of polylactic acid.

The purpose of the present invention is to find a solution that allows inclusion of greater amounts of milled spent grains, e.g. wheat distillers, without loss of strength or flexibility.

Moreover, the purpose of the present invention is to find polymer composites that can be moulded, e.g., into disposable articles such as coffee capsules, cutlery, food trays, single- serve packaging etc., whereas the polymer composites are biodegradable.

Summary of the Invention A polymer composite is provided as claimed in claim 1, comprising. a. polymer in an amount of 5-94.5% by weight of the overall weight; b. milled spent grains in an amount of at least 5% by weight of the overall weight; c. plasticizer in an amount from 5 — 50% w/w of component b); d. optional filler, and e. optional additive, wherein c) is a solid plasticizer with a melting temperature in the range of 55 to 210°C.

Also provided is a process for preparing the polymer composite, an intermediate for preparing the polymer composite and articles comprising the polymer composite.

Detailed description of the Invention It has been found that with the addition of at least 5%, preferably at least 15% by weight of a solid plasticizer based on the milled spent grains, optionally together with an appropriate filler, the milled spent grains can form a plastic composite material with a thermoplastic polymer even at high loading levels, e.g., higher than 40% w/w based on the milled spent grains and polymer.

For use in the present invention, any type of spent grains as defined above can be used as component b). This current invention specifically focusses on milled distillers’ grains based on any one or more of wheat distillers, barley distillers, maize distillers, and brewers’ grains.

Prior to compounding, the distillers’ grains are milled to a fine powder, having a particle size smaller than 1 mm, preferably smaller than 500 micrometres.

This is preferably done in

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multiple stages to obtain a uniform small particle size. For instance, milled wheat distillers powder may be used. Similar considerations apply with respect to barley distillers, e.g., using milled barley distillers powder, maize distillers, e.g., milled maize distillers powder, brewers’ grains, e.g. milled brewers’ grains powder, or combinations thereof.

Milling is preferably carried out on dry material e.g. in order to more easily obtain a uniform small particle size and/or to reduce the amount of introduced liquid such as water. In an embodiment, materials may thus be dried prior to milling. Hence, although in this specification, materials may only be referred to as being milled, the present invention alternatively or additionally refers to embodiments in which the materials are dried milled and thus, if necessary, the wording “milled” may be replaced throughout the specification by the wording “dried milled” where appropriate. In other words, “milled” has to be interpreted as meaning “milled and/or dried milled” unless specifically stated otherwise.

The milled distillers’ grains may be used at low loading levels, starting at 5% by weight of the overall weight, but preferably is used at loading levels in excess of 40%, e.g., at loading levels of 40-20%, more preferably at loading levels of 40-80%, still more preferably at loading levels of 40-70% by weight of the overall weight. The milled distillers’ grains may be mixed, e.g. up to 100%, preferably up to 50% by weight of component b), with milled expeller /meal/ cake, milled pomace, milled biscuit meal (or biscuit cereal meal), milled whole seeds, milled whole roots, milled whole beans, milled stems and/or leaves, whole grain flour of cereal grass, and flour of pulse, or combinations thereof. For instance, a mixture of two materials such as milled wheat distillers and either rosehip meal, or areca catechu leaf sheath powder may be used. When mixing the milled distillers’ grains with expellers, meals, and the like, the amount of solid plasticizer is calculated on the combined (total) weight of the milled distillers’ grains mixture.

Suitable expellers may include but are not limited to the expeller of sunflower seeds, rapeseed, linseed, peanut, palm fruit, sesame seed, castor seed, and sugar beet pulp.

Suitable meals may include but are not limited to the meal of sunflower, borage, cottonseed, Buglossoides arvensis (Ahiflower), safflower, rosehip, canola, blackcurrant, palm kernel, and evening primrose. Biscuit meal, or biscuit cereal meal, may include either a mixture of or the individual components of the crumbed waste of cooked and processed biscuit, cake and cereal food products. Cereal grasses include staple crops such as maize, wheat, rice, barley, oat and millet and hybrids such as triticale, as well as feed for animals, such as canary seeds. Pulses include annual leguminous crops yielding from one to twelve grains or seeds of variable size, shape and colour within a pod, that are used for both food and feed

-4- and that are harvested solely for dry seed, such as field peas, faba beans and lupin beans. Suitable examples of pomace may include grape pomace, olive pomace, apple pomace, or the solid remains of other fruits or vegetables after pressing for juice or oil.

The polymer composite may be made from any polymer as component a), but preferably a thermoplastic polymer is used. Suitable polymers include synthetic and natural polymers, e.g., biobased and biodegradable polymers. Suitable thermoplastic materials include polyamides (such as nylon), acrylic polymers, polystyrenes, polypropylene (PP), polyethylene (including low-density polyethylene (LDPE) and high density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS), polyglycolic acid, polycarbonates, polybenzimidazole, poly ether sulphone, polyether ether ketones (PEEK), polyetherimide, polyphenylene oxide, polyphenylene sulphide, polyvinyl chloride, and polytetrafluoroethylene, or any suitable mixture thereof.

Elastomers, or combinations of thermoplastic polymers with elastomers may also be used. Suitable elastomers include natural and synthetic rubbers, chloroprene, neoprene, isoprene, polybutadiene, butyl rubber, halogenated butyl rubber, styrene-butadiene, nitrile rubber, latex, fluoroelastomers, silicone rubbers, epichlorhydrin, poly ether block amides, ethylene vinyl acetate (EVA) and ethylene vinyl alcohol (EVOH) for example. The elastomer may comprise a thermoplastic elastomer, which may be selected from styrenic block copolymers (TPE-s), thermoplastic olefins (TPE-0}, elastomeric alloys (TPE-v or TPV), thermoplastic polyurethanes (TPU), thermoplastic copolyester (TPE-E) and thermoplastic polyamides, for example.

Thermoset polymers, or combinations of thermoplastic polymers with thermoset polymers may also be used. Suitable thermoset polymers include epoxy resins, melamine formaldehyde, polyester resins and urea formaldehyde, for example.

Suitable acrylic polymers (which may be thermoplastics, thermosets or thermoplastic elastomers) include polyacrylic acid resins, polymethyl methacrylates, polymethyl acrylates, polyethyl acrylates, polyethyl ethacrylates, and polybutyl methacrylates, for example. Suitable polyesters include polyglycolide (PGA), polylactide or poly(lactic acid) (PLA), poly(lactide-co-glycolide) (PLGA), polycaprolactone (PCL), poly(butylene succinate) (PBS) and its copolymers, poly(butylene adipate-co-terephtalate) (PBAT), a linear copolymer of N- acetyl-glucosamine and N-glucosamine with B-1,4 linkage, cellulose acetate (CA), poly(hydroxybutyrate) (PHB) or other polyhydroxyalkanoates (PHA), poly(hydroxybutyrate-

-5. co-hydroxyvalerate) (PHBV), or any suitable mixture thereof. Most preferably PLA is used as component a). Most preferably, for improved biodegradability, the polymer composite comprises PLA in an amount between 30 to 50% w/w of the overall mixture.

Plasticizers are an important class of low molecular weight non-volatile compounds that are widely used in polymer industries as additives. Plasticizers for thermoplastics are, in general, high boiling point liquids, with average molecular weights of between 300 and 600, and linear or cyclic carbon chains (14 — 40 carbons). However, the purpose of the plasticizer for a biomaterial is to prevent agglomeration of the carbohydrate / protein chains so that the biomaterial mixes with the polymer and the two become a single plastic mass. For the purpose of the present invention, the plasticizer must be compatible with component b}, and be different from component b). Whereas in the prior art the only example of a plasticizer associated with DDGS is in US patent 10,513,063, which is water or an aqueous solution of urea, the present invention requires the use of a solid plasticizer with a melting temperature in the range of 55 to 210 °C. The plasticizer may be selected from polyols, polyfunctional alcohols, amphipolar plasticizers such as carboxylic acids and esters, for instance mono, di-, and tri-glyceride esters; mono-, di- and oligosaccharides and combinations thereof. Polyols have been found to be particularly effective. Suitable plasticizers include sorbitol, maltitol, sucralose, threitol, erythritol, psicose, allose, talose, ribitol, tagatose, arabinose, galactitol, lactitol, arabitol, glyceraldehyde, iditol, sorbose, ribose, galactose, volemitol, mannitol, fucitol, xylose, xylitol, trehalose, cellobiose, raffinose, glucose, mannose, fructose, isomalt, polydextrose and sucrose; and/or combinations thereof. For instance, xylose, with a melting point of 144 to 145°C and/or sorbitol, with a melting point of 94-96°C may be used. Also a mixture of a solid plasticizer and a liquid plasticizer may be used, provided the mixture has a melting temperature in the range of 55 to 210 °C. The amount of liquid plasticizer is preferably small, e.g., up to 10% by weight of component c).

The plasticizer may be used in an amount from 15 — 50% w/w of component b), preferably between 22 — 40% w/w of component b). Additional, optional components of the polymer composite include fillers, such as mineral fillers and/or natural fibres and/or carbon-based fillers.

Suitable mineral fillers include carbonates (including bicarbonates), phosphates, ferrocyanides, silica, silicates, aluminosilicates (including all forms of clay minerals and talc), titanium dioxide, or combinations thereof. For instance, a nepheline syenite may be used or

-6- any similar filler derived from silica-undersaturated and peralkaline igneous rocks, as well as any type of bentonite. Natural fibres include cellulose or lignocellulosic fibres such as plant or vegetable fibres from the blast, leaf, seed, wood, or stem. For instance, wood cellulose fibre may be used.

Carbon based fillers include carbon nanotubes (CNT), graphene, fullerene, graphite, and amorphous carbon. The filler may be used in an amount from 0 — 96% w/w of the overall mixture, preferably between 1 — 40% w/w of the overall mixture.

Optional additional components include compatibilizers, fragrances, heat and UV stabilizers, colouring agents and the like. Suitable compatibilizers include any acrylic grafted thermoplastics (for example: maleic anhydride grafted polyethylene, polypropylene, or polylactic acid), interface-active high-molecular-weight peroxides, polv{Z-athyi-Z-oxazeline), any esters of citric acid, aromatic carbodiimides {for example: BioAdimide from Lanxess), wax-hassed emulsion additives (for example: Aguscer from BYK Additives), organc-silane coupling agents, and isocyanates {or disocyanale) coupling agents {for example: methylenedijsocyanale).

The additional components may be used in an amount from 0 — 30% by weight of the overall mixture, preferably between 0 — 15% by weight of the overall mixture.

The polymer composite is made by so-called “hot compounding” techniques, where the components are combined under heat and shearing forces that bring about a state of molten plastic (fluxing) which is shaped into the desired product, cooled and allowed to develop ultimate properties of strength and integrity. Hot compounding includes calendering, extrusion, injection and compression moulding. This is carried out at temperatures, pressures and processing conditions specific to the selected polymer. For instance, when using PLA the temperature is preferably in the range of 130 to 210°C, preferably between 130 to 165°C.

The polymer composite may also be made by a multistep process, wherein the milled spent grains is first compounded with the solid plasticizer and pelletized and the pellets or grinded pellets are then combined with the polymer. Additional components may be added in any of the steps of the multistep process. The present invention therefore also provides pellets or grinded pellets of milled spent grains compounded and pelletized with plasticizer and other components if any, as intermediate product for combination with the polymer to produce the polymer composite.

-7- The result of the process can be in the form of a solid article (or layer or portion thereof) and may comprise a compounded pellet, extruded work-piece, injection-moulded article, blow moulded article, film or rota-moulded plastics article, two-part liquid moulded article, laminate, 3D printer filament, felt, woven fabric, knitted fabric, embroidered fabric, nonwoven fabric, geotextiles, fibres or a solid sheet, for example. The solid article may be in the form of a coffee pod, cutlery, food tray, or single-serve packaging.

The invention is illustrated by the below examples. Example 1 275 grams of PLA (Ingeo® 3251D from Natureworks LLC), 225 grams of milled wheat distillers and 67.5 grams of xylose was mixed in a sealed plastic bag into a homogenous mixture. This mixture was then poured into the hopper of a Negri Bossi v55 injection moulding machine with a 32 mm diameter screw and a L/D ratio of 20:1 operating at temperatures ranging from 130 to 165°C. The mixture was moulded into coffee capsules suitable for use in a Nespresso® coffee machine.

Example 2 275 grams of PLA (Ingeo 3251D from Natureworks LLC), 225 grams of milled barley distillers and 67.5 grams of xylose was mixed in a sealed plastic bag into a homogenous mixture. This mixture was then poured into the hopper of a Negri Bossi v55 injection moulding machine with a 32 mm diameter screw and a L/D ratio of 20:1 operating at temperatures ranging from 130 to 165°C. The mixture was moulded into coffee capsules suitable for use in a Nespresso coffee machine. Example 3 275 grams of PLA (Ingeo 3251D from Natureworks LLC), 225 grams of milled maize distillers and 67.5 grams of sorbitol was mixed in a sealed plastic bag into a homogenous mixture. This mixture was then poured into the hopper of a Negri Bossi v55 injection moulding machine with a 32 mm diameter screw and a L/D ratio of 20:1 operating at temperatures ranging from 130 to 185°C. The mixture was moulded into coffee capsules suitable for use in a Nespresso coffee machine.

-8- Example 4 275 grams of PLA (Ingeo 3251D from Natureworks LLC), 225 grams of milled brewers’ grains and 67.5 grams of sorbitol was mixed in a sealed plastic bag into a homogenous mixture. This mixture was then poured into the hopper of a Negri Bossi v55 injection moulding machine with a 32 mm diameter screw and a L/D ratio of 20:1 operating at temperatures ranging from 130 to 165°C. The mixture was moulded into coffee capsules suitable for use in a Nespresso coffee machine. Example 5 150 grams of PLA (Ingeo 3251D from Natureworks LLC), 192 grams of milled wheat distillers, 58 grams of xylose and 100 grams of HiFill™ N800 (nepheline syenite powder as inorganic filler from Sibelco UK Ltd) was mixed in a sealed plastic bag into a homogenous mixture. This mixture was then poured into the hopper of a Negri Bossi v55 injection moulding machine with a 32 mm diameter screw and a L/D ratio of 20:1 operating at temperatures ranging from 130 to 165°C. The mixture was moulded into coffee capsules suitable for use in a Nespresso coffee machine.

Example 6 150 grams of PLA (Ingeo 3251D from Natureworks LLC), 192 grams of milled brewers’ grains, 58 grams of xylose and 100 grams of Premium Quest™ Bentonite (calcium bentonite powder as inorganic filler from Amcol Minerals Europe Ltd) was mixed in a sealed plastic bag into a homogenous mixture. This mixture was then poured into the hopper of a Negri Bossi v55 injection moulding machine with a 32 mm diameter screw and a L/D ratio of 20:1 operating at temperatures ranging from 130 to 165°C. The mixture was moulded into coffee capsules suitable for use in a Nespresso coffee machine.

Example 7 Representative coffee capsules from Examples 1 — 6 were filled to level capacity with ground coffee grains and sealed with self-sealing aluminium coffee capsule lids. Filled pods were then tested in a standard Nespresso coffee machine to produce a volume of filtered coffee. All capsules tested produced approximately the same volume of coffee as expelled from a commercial Nespresso capsule.

Example 8 Fifteen representative coffee capsules from Example 1 (weight: 2.45 + 0.01 g) were mixed into 2 kgs of natural topsoil containing 1 kg of distilled water in a 5 L Pyrex glass beaker and then covered with 20 cm diameter watch glass. The beaker was placed inside a Unitemp

-9- temperature-controlled oven set at 58°C and left for 21 days. Upon completion of the time the soil was removed from the beaker and broken up in order to examine the disintegration, if any, of the capsules. No intact capsules were found although eight capsule bases could be identified. All pieces that could be extracted from the soil were too fragile to remove any attached soil and could therefore not be cleaned and weighed. Summary Examples 1-4 illustrate polymer composites with a high loading of milled spent grains powder. In Examples 5-6, filler materials have been used.

All formulations allowed the preparation of a disposable article, in this case a coffee capsule. The coffee capsules were strong enough to be used in a Nespresso® coffee machine, as shown in Example 7. Moreover, the coffee capsules all proved to be highly biodegradable, as shown in Example 8.

Claims (18)

-10 - CONCLUSIONS A polymer composite comprising: a. polymer in an amount of 5-94.5 wt. % of the total weight; b. milled used grains, in an amount of at least 5 wt. % of the total weight; c. plasticizer in an amount of 5-50% w/w of component b); d. optional filler, and e. optional additive, wherein c) is a solid plasticizer with a melting temperature in the range of 55 to 210°C. Polymer composite according to claim 1, wherein component a) comprises a biodegradable polymer, preferably PLA, or derivatives or polymer mixtures thereof. The polymer composite of claim 2, wherein component a) is present in an amount of 30-70 wt. % of the total weight, preferably in an amount of 30-50 wt. % of the total weight. A polymer composite according to any one of the preceding claims, wherein component b) comprises ground wheat distillate, or ground barley distillate, or ground corn distillate, or ground brewer's grains, or a mixture thereof. A polymer composite according to any one of the preceding claims, comprising a mixture of milled spent grains and up to 50% w/w of component b) of milled press residue/flour/cake, milled pulp, milled biscuit flour or individual components thereof, milled whole seeds, ground whole roots, ground whole beans, ground stalks and/or leaves, ground whole wheat flour from cereal grass, flour from pods, or a mixture thereof. A polymer composite according to any one of the preceding claims, wherein component b) or the mixture according to claim 5 is present in an amount of 30-70 wt. % of the total weight. Polymer composite according to any one of the preceding claims, comprising polyols, polyfunctional alcohols, amphipolar plasticizers such as carboxylic acids and esters, for example mono-, di- and triglyceride esters; mono-, di- and oligosaccharides, or mixtures thereof, as constituent ¢). A polymer composite according to any one of the preceding claims, wherein component c) is present in an amount of 22 to 40% w/w of component b). Polymer composite according to any one of the preceding claims, comprising as component d) either a natural fibre, preferably cellulose or -11 - lignocellulosic fibers, and/or a mineral filler preferably selected from carbonates (including bicarbonates), phosphates, ferrocyanides, silica, silicates, aluminosilicates (including all forms of germ minerals and talc), titanium dioxide and/or a carbon-based filler, or combinations thereof. A polymer composite according to any one of the preceding claims, wherein component d) is present in an amount of 1-40 wt. % of the total weight. Polymer composites according to any one of the preceding claims, comprising compatibilizers, fragrances, heat and UV stabilizers and/or colorants or a mixture thereof as additive. A method of preparing the polymer composite according to any one of the preceding claims, wherein the polymer composite is made by: of hot compounding techniques, in which the components are compounded under heat and shear forces which induce a molten plastic state {fluxing} which is formed into the desired product, cooled and allowed to develop ultimate strength and integrity properties, preferably by calendering , extrusion, injection and compression molding, The method according to the preceding claim, carried out at temperatures in the range of 130 to 210°C. The method of claim 12 or 13, performed in two steps, wherein an intermediate is first formed in a first step and the intermediate is combined with the remainder of the components in a second step. A solid article comprising the polymer composite of any one of claims 1-11. The solid article of the preceding claim, in the form of a composite granulate, extruded workpiece, injection molded article, blow molded article, film or rotomoulded plastic article, two piece liquid molded article, laminate, 3D printer filament, felt, woven fabric, knitted fabric , embroidered fabric, non-woven fabric, geotextile, fiber or a solid board. The solid article according to claim 15 or 18, in the form of a coffee capsule, cutlery, food bowl or disposable container. An intermediate as prepared by the process according to claim 14, for use in the preparation of a polymer composite according to any one of the preceding claims 1 11.